Unexplained phenomena
The following is a list of unsolved problems grouped into broad areas of physics. General physics/quantum physics * (e.g. ): Why does time have a direction? Why did the universe have such low in the past, and time correlates with the universal (but not local) increase in entropy, from the past and to the future, according to the ? Why are s observed in certain weak force decays, but not elsewhere? Are CP violations somehow a product of the second law of thermodynamics, or are they a separate arrow of time? Are there exceptions to the principle of ? Is there a single possible past? Is the moment physically distinct from the past and future, or is it merely an emergent property of ? What links the quantum arrow of time to the thermodynamic arrow? * : How does the description of reality, which includes elements such as the of states and or , give rise to the reality we perceive? Another way of stating this question regards the : What constitutes a "measurement" which apparently causes the wave function to collapse into a definite state? Unlike classical physical processes, some quantum mechanical processes (such as arising from ) cannot be simultaneously "local", "causal", and "real", but it is not obvious which of these properties must be sacrificed, or if an attempt to describe quantum mechanical processes in these senses is a such that a proper understanding of quantum mechanics would render the question meaningless. Can a resolve it? * / : Is there a theory which explains the values of all ? Is there a theory which explains why the s of the are as they are, and why observed has 3 spatial dimensions and 1 ? Do "fundamental physical constants" vary over time? Are any of the fundamental particles in the standard model of particle physics actually composite particles too tightly bound to observe as such at current experimental energies? Are there fundamental particles that have not yet been observed, and, if so, which ones are they and what are their properties? Are there ? * : Given an arbitrary , does a non-trivial quantum Yang–Mills theory with a finite exist? (This problem is also listed as one of the in mathematics.) * : Quantum chromodynamics (QCD) color confinement conjecture is that color charged particles (such as quarks and gluons) cannot be separated from their parent hadron without producing new hadrons. There is not yet an analytic proof of color confinement in any non-abelian gauge theory. * : Are there physical phenomena, such as or s, that irrevocably destroy information about their prior states? How is stored as a state of a quantum system? * : At the present time, the values of the dimensionless physical constants cannot be calculated; they are determined only by physical measurement. What is the minimum number of dimensionless physical constants from which all other dimensionless physical constants can be derived? Are dimensional physical constants necessary at all? * : The values of the fundamental physical constants are in a narrow range necessary to support carbon-based life. Is this because there exist with different constants, or are our universe's constants the result of chance, or some other factor or process? In particular, Tegmark's of parallel universe models, and the of spacetime regions having different formalized sets of laws and physical constants from that of the surrounding space — require formalization. * : Is it possible to construct, in the mathematically rigorous framework of , a theory in 4-dimensional spacetime that includes interactions and does not resort to ? Cosmology and general relativity * : In quantum mechanics time is a classical background parameter and the flow of time is universal and absolute. In general relativity time is one component of four-dimensional spacetime, and the flow of time changes depending on the curvature of spacetime and the spacetime trajectory of the observer. How can these two concepts of time be reconciled? * : Is the theory of cosmic inflation in the very early universe correct, and, if so, what are the details of this epoch? What is the hypothetical |hide=y|expected= }} that gave rise to this cosmic inflation? If inflation happened at one point, is it , and thus ongoing in some extremely distant place? * : Why is the distant universe so homogeneous when the seems to predict larger measurable of the night sky than those observed? Cosmological is generally accepted as the solution, but are other possible explanations such as a more appropriate? * and : Is the universe heading towards a , a , a , or a ? Or is it part of an infinitely recurring ? * : The diameter of the is about 93 billion light-years, but what is the size of the whole universe? * : Why is there far more than in the ? * : Why does the of the not cause a large ? What cancels it out? * : What is the identity of dark matter? Is it a ? Is it the lightest (LSP)? Or, do the point not to some form of matter but actually to an ? * : What is the cause of the observed ( ) of the universe? Why is the energy density of the dark energy component of the same magnitude as the density of matter at present when the two evolve quite differently over time; could it be simply that we are observing at exactly the ? Is dark energy a pure cosmological constant or are models of such as applicable? * : Is a non-spherically symmetric gravitational pull from outside the observable universe responsible for some of the observed motion of large objects such as galactic clusters in the universe? * : Some large features of the microwave sky at distances of over 13 billion light years appear to be aligned with both the motion and orientation of the solar system. Is this due to systematic errors in processing, contamination of results by local effects, or an unexplained violation of the ? * : What is the 3- of , i.e. of a comoving spatial section of the universe, informally called the "shape" of the universe? Neither the curvature nor the topology is presently known, though the curvature is known to be "close" to zero on observable scales. The hypothesis suggests that the shape of the universe may be unmeasurable, but, since 2003, , et al., and other groups have suggested that the shape of the universe may be the . Is the shape unmeasurable; the Poincaré space; or another 3-manifold? Quantum gravity * : Why does the predicted mass of the have little effect on the expansion of the universe? * : Can and be realized as a fully consistent theory (perhaps as a )? Is spacetime fundamentally continuous or discrete? Would a consistent theory involve a force mediated by a hypothetical , or be a product of a discrete structure of spacetime itself (as in )? Are there deviations from the predictions of general relativity at very small or very large scales or in other extreme circumstances that flow from a quantum gravity theory? * s, , and : Do black holes produce thermal radiation, as expected on theoretical grounds? Does this radiation contain information about their inner structure, as suggested by , or not, as implied by 's original calculation? If not, and black holes can evaporate away, what happens to the information stored in them (since quantum mechanics does not provide for the destruction of information)? Or does the radiation stop at some point leaving black hole remnants? Is there another way to probe their internal structure somehow, if such a structure ? * : Does nature have more than four dimensions? If so, what is their size? Are dimensions a fundamental property of the universe or an emergent result of other physical laws? Can we experimentally observe evidence of higher spatial dimensions? * The and the : Can singularities not hidden behind an event horizon, known as " ", arise from realistic initial conditions, or is it possible to prove some version of the "cosmic censorship hypothesis" of which proposes that this is impossible? Similarly, will the s which arise in some solutions to the equations of general relativity (and which imply the possibility of backwards ) be ruled out by a theory of which unites general relativity with quantum mechanics, as suggested by the "chronology protection conjecture" of ? * : Are there non-local phenomena in quantum physics? If they exist, are non-local phenomena limited to the revealed in the violations of the , or can information and conserved quantities also move in a non-local way? Under what circumstances are non-local phenomena observed? What does the existence or absence of non-local phenomena imply about the fundamental structure of spacetime? How does this elucidate the proper interpretation of the fundamental nature of quantum physics? High-energy physics/particle physics * : Why is such a weak force? It becomes strong for particles only at the , around 1019 , much above the (100 GeV, the energy scale dominating physics at low energies). Why are these scales so different from each other? What prevents quantities at the electroweak scale, such as the mass, from getting on the order of the Planck scale? Is the solution , , or just ? * : The Planck mass plays an important role in parts of mathematical physics. A series of researchers have suggested the existence of a fundamental particle with mass equal to or close to that of the Planck mass. The Planck mass is however enormous compared to any detected particle. It is still an unsolved problem if there exist or even have existed a particle with close to the Planck mass. This is indirectly related to the hierarchy problem. * s: Did particles that carry "magnetic charge" exist in some past, higher-energy epoch? If so, do any remain today? ( showed the existence of some types of magnetic monopoles would explain .) * and : Is the proton fundamentally stable? Or does it decay with a finite lifetime as predicted by some extensions to the standard model? How do the quarks and gluons carry the spin of protons? * : Is spacetime supersymmetry realized at TeV scale? If so, what is the mechanism of supersymmetry breaking? Does supersymmetry stabilize the electroweak scale, preventing high quantum corrections? Does the lightest (LSP or ) comprise ? * : Why are there three generations of s and s? Is there a theory that can explain the masses of particular quarks and leptons in particular generations from first principles (a theory of s)? * : What is the mass of neutrinos, whether they follow or statistics? Is the mass hierarchy normal or inverted? Is the CP violating phase equal to 0? * : Why has there never been measured a free quark or gluon, but only objects that are built out of them, such as s and s? How does this phenomenon emerge from ? * and s: Why is the invariant to and ? Is the solution to this problem? Could axions be the main component of ? * : Why is the experimentally measured value of the 's anomalous magnetic dipole moment ("muon g-2") significantly different from the theoretically predicted value of that physical constant? * : What is the electric of the proton? How does it differ from gluonic charge? * s and other s: What combinations of quarks are possible? Why were pentaquarks so difficult to discover? Are they a tightly-bound system of five elementary particles, or a more weakly-bound pairing of a baryon and a meson? * : problem of theories, concerned with understanding the parameters of the theory. * : An aspect of the . The sum of the masses of the three charged leptons, divided by the square of the sum of the roots of these masses is Q=\frac 2 3 , to within one standard deviation of observations. It is unknown how such a simple value comes about, and why it is the exact arithmetic average of the possible extreme values of (equal masses) and 1 (one mass dominates). Astronomy and astrophysics * : Why do only certain s surrounding certain astronomical objects emit s along their polar axes? Why are there s in many accretion discs? Why does the period of these oscillations scale as the inverse of the mass of the central object? Why are there sometimes overtones, and why do these appear at different frequency ratios in different objects? * s: What is responsible for the numerous interstellar absorption lines detected in astronomical spectra? Are they molecular in origin, and if so which molecules are responsible for them? How do they form? * s: What is the origin of the between supermassive black hole mass and galaxy velocity dispersion? How did the most distant s grow their supermassive black holes up to 1010 solar masses so early in the history of the universe? * : Why does the number of objects in the Solar System's fall off rapidly and unexpectedly beyond a radius of 50 astronomical units? * : Why is the observed energy of satellites sometimes different by a minute amount from the value predicted by theory? * : Is responsible for differences in observed and theoretical speed of stars revolving around the centre of galaxies, or is it something else? * e: What is the exact mechanism by which an implosion of a dying star becomes an explosion? * : What astrophysical process is responsible for the of these rare isotopes? * : Why is it that some cosmic rays appear to possess energies that are impossibly high, given that there are no sufficiently energetic cosmic ray sources near the Earth? Why is it that (apparently) some cosmic rays emitted by distant sources have energies above the ? * Rotation rate of : Why does the exhibit a (slowly changing) periodicity close to that at which the planet's clouds rotate? What is the true rotation rate of Saturn's deep interior? * Origin of : What is the origin of magnetic field? * : Is the universe at very large scales , making the an invalid assumption? The number count and intensity dipole anisotropy in radio, NRAO VLA Sky Survey (NVSS) catalogue is inconsistent with the local motion as derived from and indicate an intrinsic dipole anisotropy. The same NVSS radio data also shows an intrinsic dipole in polarization density and degree of polarization in the same direction as in number count and intensity. There are several other observation revealing large-scale anisotropy. The optical polarization from quasars shows polarization alignment over a very large scale of Gpc. The cosmic-microwave-background data shows several features of anisotropy, which are not consistent with the model. * : Why is space roar six times louder than expected? What is the source of space roar? * in the Galactic disk: Is there a universal age–metallicity relation (AMR) in the Galactic disk (both "thin" and "thick" parts of the disk)? Although in the local (primarily thin) disk of the there is no evidence of a strong AMR, a sample of 229 nearby "thick" disk stars has been used to investigate the existence of an age–metallicity relation in the Galactic thick disk, and indicate that there is an age–metallicity relation present in the thick disk. Stellar ages from asteroseismology confirm the lack of any strong age-metallicity relation in the Galactic disc. * : Why is there a discrepancy between the amount of lithium-7 predicted to be produced in and the amount observed in very old stars? * : The was thought to be a black hole, but in October 2014 data from NASA's space-based X-ray telescope indicated that M82 X-2 is a 1 to 2 times brighter than the . How can this pulsar remain stable, and how did it form? * s: Transient radio pulses lasting only a few milliseconds, from emission regions thought to be no larger than a few hundred kilometres, and estimated to occur several hundred times a day. While several theories have been proposed, there is no generally accepted explanation for them. The only known repeating FRB emanates from a galaxy roughly 3 billion light years from Earth. Nuclear physics " in the proton vs. neutron number plot for heavy nuclei}} * : What are the phases of strongly interacting matter, and what roles do they play in the evolution of ? What is the detailed structure of the ? What does QCD predict for the properties of strongly interacting matter? What determines the key features of QCD, and what is their relation to the nature of and ? Do s exist? Do s acquire mass dynamically despite having a zero , within s? Does QCD truly lack s? Do gluons saturate when their occupation number is large? Do gluons form a dense system called ? What are the signatures and evidences for the Balitsky-Fadin-Kuarev- , , evolution equations? * and : Why is there in estimates of the mean lifetime of a free neutron based on two separate- and increasingly precise- experimental methods? What is the nature of the that binds and into and rare isotopes? What is the nature of exotic excitations in nuclei at the frontiers of stability and their role in stellar processes? What is the nature of and dense ? What is the origin of the elements in the ? What are the nuclear reactions that drive and stellar explosions? Atomic, molecular and optical physics * : What is the momentum of light in optical media? Whether Abraham's or Minkowski's momentum is right? * : How do we rigorously prove the existence of Bose–Einstein condensates for general interacting systems? Classical mechanics * Singular trajectories in the : Does the set of initial conditions for which particles that undergo near-collisions gain infinite speed in finite time have zero? This is known to be the case when N'' = 4, but the question remains open for larger ''N. Condensed matter physics (specifically ). The mechanism for superconductivity of these materials is unknown.}} * s: What is the mechanism that causes certain materials to exhibit at temperatures much higher than around 25 s? Is it possible to make a material that is a superconductor at room temperature? * s: What is the nature of the between a fluid or regular solid and a glassy ? What are the physical processes giving rise to the general properties of glasses and the glass transition? * : Why does the electron emission in the absence of light increase as the temperature of a is decreased? * : What causes the emission of short bursts of light from imploding bubbles in a liquid when excited by sound? * : Is it possible to make a theoretical model to describe the statistics of a turbulent flow (in particular, its internal structures)? Also, under what conditions do exist? The latter problem is also listed as one of the in mathematics. * : In the solar wind and the turbulence in solar flares, coronal mass ejections, and magnetospheric substorms are major unsolved problems in space plasma physics. * : Is topological order stable at non-zero ? Equivalently, is it possible to have three-dimensional ? * : What mechanism explains the existence of the u=5/2 state in the fractional ? Does it describe quasiparticles with ? * s: Can the to (A) phase transition in liquid crystal states be characterized as a phase transition? * s: What is the cause of the nonparabolicity of the energy-size dependence for the lowest of ? * : In electrical devices, some metallic surfaces may spontaneously grow fine metallic whiskers, which can lead to equipment failures. While compressive mechanical stress is known to encourage whisker formation, the growth mechanism has yet to be determined. Plasma physics * and : Fusion energy may potentially provide power from abundant resource (e.g. hydrogen) without the type of radioactive waste that fission energy currently produces. However, can ionized gases (plasma) be long enough and at a high enough temperature to create fusion power? What is the physical origin of ? * : How does the Sun generate its periodically reversing large-scale magnetic field? How do other solar-like stars generate their magnetic fields, and what are the similarities and differences between stellar activity cycles and that of the Sun? What caused the and other grand minima, and how does the solar cycle recover from a minima state? * : Why is the Sun's corona (atmosphere layer) so much hotter than the Sun's surface? Why is the effect many orders of magnitude faster than predicted by standard models? * : is thought to be the primary mechanism that accelerates astrophysical particles to high energy. However, it is unclear what mechanism causes those particles to initially have energies high enough for Fermi acceleration to work on them. * : In 2007 the passed through the tail of comet (McNaught) and found surprising results concerning the interaction of the solar wind with the tail. Biophysics * and robustness to in : How do genes govern our body, withstanding different external pressures and internal ? exist for genetic processes, but we are far from understanding the whole picture, in particular in where gene expression must be tightly regulated. * : How is long-term memory stored on a biological substrate undergoing constant turnover? * Quantitative study of the : What are the quantitative properties of s? What are the basic building blocks of networks? * : How to unify and ? * : What is the origin of the of specific in s? Science Frontiers Sourcebook Project Books published by include: *''Mysteries of the Universe'' (1967) *''Mysteries Beneath the Sea'' (1970) *''Strange Phenomena: A Sourcebook of Unusual Natural Phenomena'' (1974) *''Strange Artifacts: A Sourcebook on Ancient Man'' (1974) *''The Unexplained'' (1976) *''Strange Life'' (1976) *''Strange Minds'' (1976) *''Strange Universe'' (1977) *''Handbook of Unusual Natural Phenomena'' (1977) *''Strange Planet'' (1978) *''Ancient Man: A Handbook of Puzzling Artifacts'' (1978) *''Mysterious Universe: A Handbook of Astronomical Anomalies'' (1979) *''Unknown Earth: A Handbook of Geological Enigmas'' (1980) *''Incredible Life: A Handbook of Biological Mysteries'' (1981) *''The Unfathomed Mind: A Handbook of Unusual Mental Phenomena'' (1982) *''Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena'' (1982) *''Tornados, Dark Days, Anomalous Precipitation, and Related Weather Phenomena'' (1983) *''Earthquakes, Tides, Unidentified Sounds, and Related Phenomena'' (1983) *''Rare Halos, Mirages, Anomalous Rainbows, and Related Electromagnetic Phenomena'' (1984) *''The Moon and the Planets'' (1985) *''The Sun and Solar System Debris'' (1986) *''Stars, Galaxies, Cosmos'' (1987) *''Carolina Bays, Mima Mounds, Submarine Canyons'' (1988) *''Anomalies in Geology: Physical, Chemical, Biological'' (1989) *''Neglected Geological Anomalies'' (1990) *''Inner Earth: A Search for Anomalies'' (1991) *''Biological Anomalies: Humans I'' (1992) *''Biological Anomalies: Humans II'' (1993) *''Biological Anomalies: Humans III'' (1994) *''Science Frontiers: Some Anomalies and Curiosities of Nature'' (1994) *''Biological Anomalies: Mammals I'' (1995) *''Biological Anomalies: Mammals II'' (1996) *''Biological Anomalies: Birds'' (1998) *''Ancient Infrastructure: Remarkable Roads, Mines, Walls, Mounds, Stone Circles: A Catalog of Archeological Anomalies'' (1999) *''Ancient Structures: Remarkable Pyramids, Forts, Towers, Stone Chambers, Cities, Complexes: A Catalog of Archeological Anomalies'' (2001) *''Remarkable Luminous Phenomena in Nature: A Catalog of Geophysical Anomalies'' (2001) *''Scientific Anomalies and other Provocative Phenomena'' (2003) *''Archeological Anomalies: Small Artifacts'' (2003) *''Archeological Anomalies: Graphic Artifacts I'' (2005) Category:Physics